1. Field of the Invention
The present invention relates to spool cores for the wet treatment of threads and yarns, and in particular to perforated spool cores of thermoplastic or thermosetting plastic material, suitable for wet treating spun or twined yarns, especially for the dyeing of yarn spools.
2. Description of the Prior Art
Synthetic threads and yarns are mostly dyed on cross spools wound onto cylindrical or tapered cores of plastic material. Of greatest importance in connection with the dyeing of such cross spools is the uniformity of color penetration, or color uniformity. In practice, this requirement is often very difficult or impossible to satisfy, color uniformity problems arising especially in the end zones of the spools, both at the foot end and at the head end of the spool core. This happens especially then, when the material is spooled too far beyond the perforated surface portion of the core in the direction of the core foot or core head, with the resultant creation of border zones on the spools which are being compressed against the spacer discs positioned between adjacent spools on the dyeing spindles. In such a situation, it often happens that the dye penetration is inadequate and that the desired color uniformity is not achieved.